In recent years, various services using a computer network are being realized owing to the spread of Internet and a satellite communication. As one of the services using such a computer network, a system for performing the following music distributing service has been proposed.
In FIG. 14, reference numeral 501 denotes a contents server and 502 indicates a user machine. A plurality of music data has been accumulated as contents in the contents server 501. A storage device 504 such as hard disk drive, optical disk drive, or the like is connected to the user machine 502 and a card reader/writer 505 for charging is also connected thereto. A card 506 is loaded into the card reader/writer 505.
In case of using the music distributing service, the user machine 502 is connected to the contents server 501 through a transmission path 503. The transmission path 503 is, for example, a computer network such as Internet. When the user machine 502 is connected to the contents server 501, a list of contents or a search picture plane is sent from the contents server 501 to the user machine 502.
The user searches desired contents by the list of contents or search picture plane and selects contents to be downloaded. When the user selects the contents, a requesting command of the contents is sent from the user machine 502 to the contents server 501. In the contents server 501, the contents is taken out in response to the requesting command and this contents is transmitted from the contents server 501 to the user machine 502. The contents is stored into the storage device 504 of the user machine 502. At this time, proper charging is performed by the card reader/writer 505.
If such a music distributing system is spread, the user can easily obtain the music data of a desired music piece via a communication. A server in such a system is equipped with a searching function. By using such a searching function, the user can easily search a desired music piece and obtain it. Further, in the server in such a system, since the music data is always updated, a latest music piece can be early obtained.
However, in a system such that the music data is distributed from the server to the user machine as mentioned above, there is a danger that the data of the contents is copied without permission and the right of author is not protected. Therefore, it is necessary to add a function for prevention of copy so that the data of the contents is not copied without permission and to perform proper charging for the contents.
In such a system, it is considered to reproduce the downloaded music data by another equipment or transfer it to other people. If the system is constructed so that the data of the contents is always moved to only one equipment, there is no possibility that an illegal copy is distributed. However, if the copy to the other equipment is perfectly inhibited, such a movement of the data of the contents cannot be performed as well.
In a system which can distribute contents, therefore, it is an object of the invention to provide an information distributing system which can sufficiently protect the contents and perform legal charging.